The present patent application claims the right of priority under 35 U.S.C. xc2xa7119 (a)-(d) of German Patent Application No. 101 06 458.6, filed Feb. 13, 2001.
The present invention relates to a process for the production of composite molded articles comprising at least one base body, at least one first thermoplastic part and at least one second thermoplastic part that are concurrently formed and joined to the base body by injection molding. The first and second plastic parts may be composed of different plastic materials. The base body is first placed in a multicomponent injection molding tool having at least two separate melt flow-way systems (melt injection passages or ports) and at least two cavities for each of the first second plastic parts. The plastic materials from which the first and second plastic parts are formed, are then concurrently injected into the cavities, followed by removing the composite part from the mold. BACKGROUND OF THE INVENTION
The fabrication of injection molded parts by means of multicomponent production technology is generally known. Such known processes typically involve injecting the individual plastic components, in succession, into a plurality of separate molds in a base body.
A generic process has furthermore become known from specification DE 3 503 036 A1, in which a first hollow space is filled with a first thermoplastics material by means of movable cores in a first step, and then in a second step a further hollow space is formed by withdrawing a moveable tool element. A second plastics component is then injected into the remaining hollow space and partially joined to the first plastic component.
A disadvantage of such known generic processes is that they typically have a long cycle time. One has to wait for the first plastics component to cool down since otherwise the structure of the first plastics part would be damaged. In addition, such processes typically require the use of complicated tools having special slide bars.
The object of the present invention is accordingly to provide a process that avoids the aforedescribed disadvantages of the known processes, and at the same time allows for the formation of a specific interlocking connection between the various plastics parts composed of different plastic materials.
This object is achieved according to the invention where, in a process of the type mentioned in the introduction, a base body is placed in an injection molding tool, the base body separating the cavities for the plastic parts from one another by corresponding and abutting sealing edges in the tool. A simultaneous injection of the various plastics materials into the cavities is thereby made possible. The base body also serves to join the various plastic parts formed by means of the simultaneous injection.
In accordance with the present invention, there is provided a process for producing a composite molded article comprising,
(i) at least one base body (1) having a contoured surface,
(ii) at least one first thermoplastic part (4, 5, 6), and
(iii) at least one second thermoplastic part (2, 3), each of said first and second thermoplastic parts being joined to said base body, said process comprising:
(a) providing a multicomponent injection molding tool (20) having at least two separate melt flow-way systems and at least two cavities in which each of the first and second thermoplastic parts are separately formed, each of said cavities being in separate communication with each of said separate melt flow-way systems;
(b) placing said base body into said molding tool, said cavities being separated from each other by the contoured surface of said base body and sealing edges of said molding tool that abut the contoured surface of said base body;
(c) injecting simultaneously a thermoplastic material into each of said cavities by means of said separate melt flow-way systems; and
(d) removing said composite molded article from said molding tool,
wherein said first thermoplastic part (ii) and second thermoplastic part (iii) each become joined to said base body (i) during said injection molding step (c).
The features that characterize the present invention are pointed out with particularity in the claims, which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages and the specific objects obtained by its use will be more fully understood from the following detailed description and the accompanying drawings in which preferred embodiments of the invention are illustrated and described.
Other than in the examples, or where otherwise indicated, all numbers or expressions, such a those expressing structural dimensions, etc, used in the specification and claims are to be under stood as modified in all instances by the term xe2x80x9cabout.xe2x80x9d